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Does evaporated milk contain lactose?
I am lactose intolerant, and I'm usually careful to read the label of any food or drink item that I think might contain lactose. Salt-water taffy didn't strike me as something that I should be concerned about until after the fact. I read the ingredients on the box, and the taffy contained evaporated milk. Is evaporated milk lactose free?

Does cooking affect lactose?
Lactose is a sugar that is made up of two different sugar molecules. The disaccharide (di for two and saccharide for sugar) is made up of the two sugar molecules galactose and glucose. The bond that holds these two sugars together is broken by an enzyme called lactase. The reason that many folks are lactose intolerant is because their bodies don't make the enzyme lactase.

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Managing Lactose Intolerance

Chances are you know someone who is lactose intolerant. After all,
about 20% of Caucasians, over 50% of Hispanic Americans, 75% of those
of African descent, almost 80% of Native American Indians and 80%
of Asians are lactose intolerant to some degree.

For most lactose-intolerant people, managing their condition often
means avoiding dairy products altogether, even though most people
can tolerate small amounts of lactose with no problem. As the amount
of lactose consumed increases, however, the severity of symptoms usually
increases. Researchers at the National Institute of Health noted this and
decided to review the existing evidence to find out: first, what amount
of lactose a lactose-intolerant person could consume on a daily basis without
experiencing symptoms, and second, if any of the typical treatments could
be said to work (Annals Int Med 2010;152(12):797-803).

They began by identifying those studies that had focused on lactose
dosing and managing the symptoms of lactose intolerance. Of these,
26 studies compared the effects of lactose-reduced milk or milk supplements
to the effects of regular milk, while 1 study compared milk alone to milk
along with such lactase supplements Lactodigest, DairyEase or Lactaid.
They concluded from these results that lactose is better tolerated in combination
with other foods than when milk or lactose-containing foods are eaten alone.

Further, it appeared that the minimum threshold for experiencing
symptoms is about 12 grams of lactose - alone, as a single dose.
(12 grams of lactose is about the amount of lactose in a cup of milk or
the same amount of whole-milk yogurt). However, when eaten in combination
with other foods, the threshold amount of lactose was higher - between
15 and 18 grams of lactose. Over 18 grams seemed to more reliably produce
symptoms, but it was only the comparatively large amount of 50 grams of
lactose that "induced
symptoms in most individuals."

Some of those who are lactose intolerant use probiotics in their
yogurt to help reduce their symptoms. Typically these are strains
of the bacteria Lactobacillus acidophilus which are added to the yogurt
before eating. The 7 studies that were assessed were small and not well
designed, leading the researchers to conclude that there was also not enough
evidence to say whether the strategy worked.

Another strategy for improving one's tolerance for lactose is to
eat increasing amounts of lactose over time: the reasoning is that
the colon slowly adapts to the lactose. After evaluating two studies,
the NIH researchers concluded that there wasn't enough evidence to support
this strategy, either: these studies were also too small and did
not do enough to eliminate the possibility that the participants were not
experiencing a placebo effect (in this case, experiencing symptoms because
they expected to have symptoms and not because they had actually consumed
lactose).

What this means for you

It's obvious that more, larger, and better-designed studies are needed
to assess the various treatments of lactose intolerance and how well
(or if) they work. It seems clear, however, that most people can
tolerate up to a cup of milk without symptoms as long as that milk
is in combination with other foods. The take-home message: if you're lactose-intolerant,
there's a good chance that you can enjoy dairy ingredients in your
foods, including milk in baked products and butter in your sauces.
Here's a list
of common dairy foods and the amount of lactose they
contain.